I don't tolerate mannitol/sorbitol used by other brands but the small bit of lactose in this seems OK. I found this one works better when put between the gum and lip - under the tongue it dissolves too fast. I'm going to try California Xtracts and Jarrow Formulas instead. 1) Pure Advantage methyl-B12 spray - ineffective (I wonder about the sorbate preservative in it); 2) InterPlexus Inc NutriSorb liquid hydroxycobalamin - effective but still needs to be 'converted' to active form - I found the one drop dose suggested on label isn't enough; 3) Solgar cyanocobalamin 1mg sublingual - dissolves too fast and not as effective as active methyl-B12; 4) Source Naturals methyl-B12 1mg sublingual - contains mannitol and sorbitol. Iodine/B12 are synergists - suggest adding/increasing either one if taking more of the other, especially long term. Same is true of other nutrients such as manganese and zinc (both need cobalt, high cobalt may deplete them) - could be why some people note headaches after taking high doses of B12 (both high and low manganese can cause migraine-headaches). High doses of B12 will also deplete iron - they are antagonists. If this review was helpful to you, please click YES below - thank you. For reviews of all the products I have purchased from iHerb, please click my username above.